/*
 * Copyright 2007-2008 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */

package jsr203.nio.file.attribute;

import java.io.IOException;

/**
 * An object to lookup user principals by name. A {@link UserPrincipal}
 * represents an identity that may be used to determine access rights to objects
 * in a file system. A {@code UserPrincipalLookupService} defines methods to
 * lookup identities by name or group name (which are typically user or account
 * names). Whether names and group names are case sensitive or not depends on
 * the implementation. The exact definition of a group is also implementation
 * but typically a group represents an identity created for administrative
 * purposes so as to determine the access rights for the members of the group.
 * In particular it is implementation specific if the <em>namespace</em> for
 * names and groups is the same or is distinct. Where the namespace is the same
 * then invoking {@link #lookupPrincipalByName lookupPrincipalByName} to lookup
 * a name may return a user principal representing a group, and invoking {@link
 * #lookupPrincipalByGroupName lookupPrincipalByGroupName} to lookup a group
 * may return a user principal that is not a group. To ensure consistent and
 * correct behavior across platforms it is recommended that this API be used as
 * if the namespaces are distinct.
 *
 * @since 1.7
 */

public interface UserPrincipalLookupService {

    /**
     * Lookup a user principal by name.
     *
     * @param   name
     *          The string representation of the user principal to lookup
     *
     * @return  A new user principal
     *
     * @throws  UserPrincipalNotFoundException
     *          The principal does not exist
     * @throws  IOException
     *          If an I/O error occurs
     * @throws  SecurityException
     *          In the case of the default provider, and a security manager is
     *          installed, it checks {@link RuntimePermission}<tt>("lookupUserInformation")</tt>
     */
    UserPrincipal lookupPrincipalByName(String name) throws IOException;

    /**
     * Lookup a user principal by group name.
     *
     * <p> Where an implementation does not support any notion of groups then
     * this method always throws {@link UserPrincipalNotFoundException}.
     *
     * @param   group
     *          The string representation of the group to lookup
     *
     * @return  A new user principal.
     *
     * @throws  UserPrincipalNotFoundException
     *          The principal does not exist
     * @throws  IOException
     *          If an I/O error occurs
     * @throws  SecurityException
     *          In the case of the default provider, and a security manager is
     *          installed, it checks {@link RuntimePermission}<tt>("lookupUserInformation")</tt>
     */
    UserPrincipal lookupPrincipalByGroupName(String group) throws IOException;
}
